1). Field of the Invention
This invention relates generally to a system for burn-in testing of electronic devices.
2). Discussion of Related Art
When fabrication of electronic devices, such as computer processors and memories, has been completed, the electronic devices are subjected to burn-in and electrical tests in order to identify and eliminate defective devices before shipment to customers. The term “burn-in” relates to operation of an integrated circuit at a predetermined temperature or temperature profile, typically an elevated temperature in an oven. Certain operating electrical bias levels and/or signals are supplied to the electronic devices while they are at the elevated temperature. The use of the elevated temperature accelerates stress to which the devices are subjected during bum-in, so that marginal devices that would otherwise fail shortly after being placed in service fail during burn-in, and are eliminated before shipping.
The electronic devices are usually located within burn-in sockets that are mounted to a burn-in board substrate. The burn-in board substrate is then inserted into an oven, and edge fingers on the burn-in board substrate are inserted into an edge finger socket in a rear of the oven. A driver board assembly is located externally of the oven, and is connected to the edge finger socket on a feedthrough board. Signal currents are provided from the driver board assembly through the feedthrough board, the edge finger socket on the feedthrough board, and the edge fingers to the electronic devices in the sockets on the burn-in board substrate. Power current is also provided from the driver board assembly through the socket and the edge fingers to the electronic devices.
The magnitude of the power that can be provided through edge fingers is generally relatively small, typically on the order of 3 to 5 A per finger. Certain devices, for example, computer processors, now require power currents having larger magnitudes than what can practically be achieved through edge finger connectors. In many cases, it may also be required to monitor power current that is provided to each individual device. Existing systems, however, are not adapted for providing individual power current to individual devices, and therefore also do not lend themselves to monitoring of power currents that are provided individually to each electronic device per finger.
Another disadvantage of using edge finger connectors is that they can only be located on an edge of a substrate, and therefore provide a limited amount of real estate for adding additional signal, power, ground, and other lines.